Numerous industrial processes produce aqueous streams containing significant amounts of various forms of nitrogen and sulfur contaminants. Such aqueous streams pose serious problems, to the extent that the water cannot be directly disposed of in streams, ponds or the like without the pollution of streams, ponds, groundwaters, etc. Accordingly, in order to prevent such pollution, it is necessary to purify such waters prior to disposal. Numerous methods of treating such waters includes steam stripping, flue gas stripping, air oxidation, biological treatment, chemical oxidation, solvent extraction, settling and various combinations of such techniques. However, such treatments add significantly to the cost of industrial operations and the pollutants removed create disposal problems. In addition, unless the volume of the removed pollutants is sufficiently high, it is either uneconomic or impractical to convert the same to useful products and thus reduce the cost of the operation.
There are also numerous industrial operations in which fluids containing insignificant amounts of acidic materials are processed, such as in the distillation of such fluids. As a result, these acidic materials cause corrosion, plugging and fouling of processing equipment, flow lines, etc. Accordingly, in such cases, it is often desirable to treat such fluids to neutralize the acidic materials and thus reduce corrosion and the deposition of solids. However, in such cases, the materials utilized to neutralize the acid materials add significantly to the cost of the operation.
While the present invention is applicable to the solution of the above-mentioned problems in all industrial operations, all of these problems exist and are particularly serious in petroleum refining operation. Accordingly, the following description will be confined to such petroleum refining operations for clarity of description.
Crude oils which are processed in petroleum refineries generally contain a wide variety of contaminants which, if not removed, cause serious pollution problems and unacceptable finished products. For example, most crudes contain varying amounts of nitrogen, sulfur, chlorine, metals and other contaminants in elemental, ionic or compound form, as well as various amounts of water, and the subsequent treatment of crude oil to produce useful products results in the presence of contaminants, such as water, or form contaminate materials from materials present in the crude oil. The above-mentioned problems have recently been further exaggerated by the necessity of refining less desirable crudes which contain substantially larger amounts of contaminants and alternate sources of oil, such as shale oils, oils derived from coal, oils derived from tar sands, etc. Obviously, also, these problems will increase still further in the future as a result of the necessity of using alternate sources of oil. By way of specific example, the catalytic hydrodesulfurization and/or hydrodenitrogenization of oils containing nitrogen and sulfur contaminants, such as crude oils, residium (top crude), gas oils, heating distillates, kerosene, napthas and the like result in the production of vapor streams containing nitrogen and sulfur contaminants. There are also numerous other refining processes which utilize hydrogen as a treating agent which result in the same type of vapor streams. Catalytic cracking or catalytic hydrocracking of residums (top crude, virgin gas oils, and the like) also produce vapor streams containing sulfur and nitrogen contaminants, to the extent that the feed material treated contains these contaminants. Such vapor streams also contain varying amounts of water, to the extent that the feed stream being treated contains water. In addition, water or steam is often utilized to scrub these contaminants from such vapors, thereby producing aqueous streams containing the contaminants. There are also various refining operations which utilize steam as a source of heat or as a diluent thus producing an aqueous stream often containing the above-mentioned contaminants.
Numerous refining operations also involve the treatment of fluids containing acidic materials, such fluids containing sulfur and chlorine. For example, in the fractional distillation of crude oils to recover gasoline, various distillates, etc., vapors are produced which contain these acidic materials. As a result, the distillation equipment, as well as flow lines through which the vapor passes and subsequent equipment for treating the vapor stream are corroded seriously, the contaminants also react with various anions present in the crude and the resultant salts tend to deposit on the trays, bubble caps, packing flowlines, etc., requiring cleaning at frequent intervals.